1. Field of the Invention
This invention relates to extrusion machines for mixing and working compounds such as rubber, plastics, polymers, and more particularly the invention comprises a seal arrangement for retaining heat transfer fluid used in such a machine.
2. Prior Art
In the processing of plastic or polymer material, as practiced today, the cold material is introduced into the mixing, processing or fabricating apparatus wherein it is melted and transported through or into various die means to form the material into desired shapes. Due to differences in the physical characteristics, heat capacities, density, viscosities and other factors inherent in the various feed materials, the heating, melting/cooling zones must be adaptable to the vageries of various materials and their physical requirements.
Maintenance of these physical requirements can be difficult, especially in extruding machines that are very long, and which have high heat transfer requirements, of the order of 100-120 BTU/HR/FT.sup.2 /F.degree.. The heat requirements for some polymers may lie in the range of 300.degree. F.-700.degree. F. Other materials may require cooling along various portions of their processing. The cooling temperatures required may be as low as 50.degree. F. The fluid which would provide the heat transfer medium on the material being processed, could be at pressures as high as 800 psi.
Large extruding machines of the prior art have used adjustable packing as seals between longitudinally adjacent ends of coaxial portions of the extrusion machines. The adjustable packing is asbestos or teflon in between a collar and a flange of adjacent cylinders to keep them tight and leakproof. The present invention adapts a seal design used in sealing joints of adjacent pipe members. Heretofore, this concept has not been adapted to provide a pressure resistant leakproof seal for extruding machines. The seal of the pipes were containing an internal pressure from escaping outwardly. The present invention prevents heating fluid or cooling fluid from leaking from the outwardly disposed heat transfer fluid flow path, which is between a pair of coaxial spaced apart cylinders, into the material being processed within the bore of the extruding machine.